This project is part of an ongoing study to define the pathogenesis and pathophysiology of the autosomal dominant form of familial neurohypophyseal diabetes insipidus (FNDI). In the last 4 years, we and others have determined that FNDI is linked to diverse mutations in the coding region of the gene for the polypeptide precursor (AVP-NPII). We postulate that FNDI is due to selective destruction of AVP-producing neurohypophyseal neurons by a mutant precursor that gradually accumulates and disrupts the cells because it cannot be processed properly.